<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <ul>
            <li v-for="(item,index) in arr">
                {{index}} : {{item}}
            </li>
        </ul>
        <button @click="add">添加</button>
        <button @click="remove">移除</button>
    </div>
    <script src="../../js/vue.js"></script>
    <script>
        var vue = new Vue({
            el: '#app',
            data: {
                arr: [1, 2, 3, 4]
            },
            methods: {
                add: function() {
                    this.arr.push(5);
                },
                remove: function() {
                    this.arr.shift();
                }
            },
        });
    </script>
</body>
</html>